Wednesday, September 30, 2009

After subjecting southern MB to 9 months of below normal temperatures, Mother Nature relented in dramatic fashion by delivering the warmest September on record across much of the southern Prairies. In Winnipeg, the month finished with an average temperature of 17.7C at YWG airport, over 5 degrees above the normal 12.3C and the warmest September in Winnipeg since records began in 1872. The month was nearly a full degree warmer than the previous warmest September of 1948 at 16.8C. In fact, September 2009 had a monthly mean of 19.0C through the 26th, before 4 days of cool weather at the end of the month shaved over a degree off the final average.

September 2009 was a summer-like month with plenty of sunny warm days, and only 4 days with measurable rain. The stretch between the 13th and 25th was especially nice, dominated by sunshine and 25-30C temperatures that was interrupted only one day with cloudy skies and a brief shower over the two week period. The month finished with an average temperature higher than any month of the year, the first and only time in Winnipeg’s climate history that September was the warmest month of the year. Every day from the 1st to the 27th was above normal with 19 of those days reaching a temperature of 25C or higher, the most 25C days of any September (previous record 16 days in 1940) and nearly twice as many as July had (10 days) Amazingly, no daily record highs were established during the month, highlighting the fact that it was the persistence of the warm weather that was the story, rather than any extreme heat. This was evident with the night-time lows, with no lows below 10C until the 22nd. A cool snap at the end of the month produced the season’s first frost on the 29th with a low of -2.4C at Winnipeg airport. Downtown however remained frost free all month.

Precipitation at the airport totaled 22 mm, less than half the average September monthly precipitation of 58 mm. Of the 22mm total, only 1 mm fell after the 11th. The sunny dry warm weather was a blessing for area farmers who needed an extended period of warm dry weather to make up for a slow growing season delayed by cool temperatures and rainfall. As a result, many crops were able to mature before the late frost, and be harvested in fine sunny conditions. The weather was also a boon to local beaches and golf courses, making up for some lost ground from a cool wet summer.

Tuesday, September 29, 2009

Clear skies and a light wind allowed temperatures to drop to below freezing this morning across much of southern MB, officially ending the 2009 growing season. The exception was near Lake Winnipeg and western MB where clouds kept temperatures above freezing overnight (see map) At Winnipeg airport, the temperature dropped to a low of -2.4C, ending a 114 day growing season that began late due to a record freeze on June 6th.

At Winnipeg airport, the average date of the first fall frost is Sept 22nd so today's frost was a week later than "normal", although the first fall frost date varies quite a bit from year to year. Average date for the last frost in spring is May 23rd which gives an average growing season of about 121 days using airport data. Last year, the airport had a 116 day growing season (Jun 3rd - Sept 26th), virtually the same as this year.

Within the city of Winnipeg however, frost was not widespread this morning. The Forks downtown had a low of +1.4C, and in Charleswood, my station registered a low of +0.5C with just some some light frost noted. Downtown Winnipeg has a much longer growing season than the airport, due to the urban heat island effect that keeps night time temperatures warmer than rural areas. The average first fall frost downtown is Oct 5th, while the last spring frost is May 4th giving an average growing season of 159 days downtown, or 38 days longer than the airport. For most areas of the city, the length of the growing season lies somewhere between downtown and airport values.

Monday, September 28, 2009

No, that's not a Wendy's menu order.. that's the weather forecast for Winnipeg and southern Manitoba for the next 24 hours as a northerly flow of cool air spreads over the province. Gusty north winds today will keep temperatures only in the 12c range this afternoon, with cloudy skies and occasional sprinkles or drizzle from weakening off lake streamers. For tonight, high pressure will be building over southern MB, bringing clearing skies and diminishing winds.. perfect conditions for frost formation overnight. In fact, much of southern MB will see its first frost of the season by Tuesday morning with overnight lows of zero to -3C expected. The exception will be areas near and to the west of the MB lakes which will be saved from frost by the warm lake waters. Patchy cloud cover will also save some localities from frost tonight. Tuesday looks like a nice day with sunshine mixing with a few clouds, lighter winds, and afternoon temperatures of 12-15C.

Friday, September 25, 2009

The extended summerlike pattern of September 2009 will come to an abrupt end Sunday as a storm system tracks across Manitoba and intensifies over northwest Ontario Sunday night. Strong northwest winds on the backside of this system will draw in much cooler air over southern MB Sunday into Sunday night, with gusts of 70 to 80 km/h likely by Sunday evening over much of southern MB, with 90-100 km/h gusts possible on the eastern shores of Lakes Winnipeg and Manitoba. These strong winds will combine with high lake levels to create large waves.. possibly 3-4 metres high, which may cause problems along the exposed eastern shorelines of the lakes. In addition, the strong winds may result in tree limb damage and local power outages since most trees are still full of leaves thanks to a warm frost-free September. A similar storm system on June 27th brought 100 km/h gusts over southern Lake Winnipeg and resulted in extensive power outages through cottage country into the Whiteshell due to fallen tree limbs and power lines.

Wednesday, September 23, 2009

The summer-like weather of September 2009 will be one for the record books. With a maximum temperature of 26C Wednesday, Winnipeg registered its 17th day in September with temperatures of 25C or higher. This eclipses the previous September record of sixteen 25C days set back in 1940. And it looks like we'll add a couple more to the total before the week is through as temperatures of 25C or more are forecast both Thursday and Friday. This is in stark contrast to a very cool July, the 5th coolest on record, in which Winnipeg saw only ten days of 25C or more. In fact, September 2009 will finish with an average temperature greater than July, the first time that has ever happened in Winnipeg since records began in 1872.

The warm weather has been persistent for the past 3 weeks over southern MB with every day this month above normal so far. But changes are on the way. A storm system is expected to cross southern MB Sunday, which will draw in much cooler air Sunday into Monday on strong northwest winds. This will bring the first spell of below normal temperatures in over 3 weeks, with the risk of a widespread frost by Tuesday morning. The cool outbreak however should not be enough to offset this September finishing as the warmest September on record in Winnipeg as well as most of southern MB.

Tuesday, September 22, 2009

Fall officially arrived today at 4:18 pm CDT, but you wouldn't have known it as sunny warm weather prevailed over southern Manitoba today. And the fine late summer weather will continue the rest of the week with sunny skies and temperatures in the mid 20s.. some 10 degrees above normal for the end of September. Changes are coming though by this weekend as an intensifying storm system moves across Manitoba and drags colder air into the Prairies by Sunday along with some rainshowers. More typical fall like weather is expected to close out the last few days of September, which should finish as the warmest on record in Winnipeg, as well as over much of the Prairies.

Sunday, September 20, 2009

This was the scene in Grand Beach yesterday as temperatures soared to the 30 degree mark over much of southern MB Saturday. People flocked to the beaches on the last official weekend of the summer of 2009, a summer that was plagued by rain and cool temperatures. Locals say this is the busiest they have ever seen Grand Beach in September.. thanks to some late summer weather that has persisted most of the month. Click here for the Free Press article on summer's last hurrah.

Friday, September 18, 2009

It looks like Mother Nature is trying to make up for her abysmal performance this summer with a glorious stretch of sunny warm weather heading into the last official weekend of summer. Temperatures have been above 25C all week long with sunshine, and the warm weather will continue through the weekend before a cold front moves through late Sunday. Saturday will see temperatures rise to the 30 degree mark over much of southern MB, especially over western MB where temperatures of 32C are forecast. Sunday will continue to be warm, with gusty southerly winds pushing temperature into the mid 20s before clouds approach in the afternoon and evening ahead of the advancing cold front. This front will usher in occasional showers Sunday night into Monday with a return to more seasonable temperatures in the upper teens. However, long range models are now indicating that the cooler weather will be short lived as above normal temperatures are forecast to return by mid to late week. This virtually ensures that September 2009 will likely go down as the warmest September on record in Winnipeg since records began in 1872. After 9 consecutive months of below normal temperatures, it’s the least we deserve!

Monday, September 14, 2009

With a high of 27C this afternoon, today marked the tenth day of 25C or greater temperatures in Winnipeg so far this month.. matching the total number of 25C days recorded all of July. And it looks like we'll add a few more 25C days this week as the summer-like weather continues over southern MB with sunny skies and well above normal temperatures through Wednesday. There will be a brief cooldown Thursday into Friday as a backdoor cold front tries to push cooler air into southern MB. However, windy and warmer conditions will return this weekend with gusty southerly winds pushing us back into the mid to upper 20s. Long range models are indicating a change to cooler weather by next Monday as we approach the official first day of fall on Sept 22nd. In the meantime, enjoy the summer weather denied to us the past 3 months!

Friday, September 11, 2009

Today's wet weather will give way to drier conditions for the weekend.. with temperatures remaining above normal for this time of year. Saturday will see partly cloudy skies with the chance of a stray shower, with highs in the low 20s. Sunday is looking very nice with sunshine , light winds, and high temperatures climbing into the mid 20s. Warm dry weather is expected for the first part of the week with highs in the mid to upper 20s, with a chance of some showers and slightly cooler conditions by Wednesday or Thursday. Still.. temperatures are expected to remain above normal through next weekend as the summery September of 2009 continues.

Thursday, September 10, 2009

It will be another warm day today over southern MB with sunshine and temperatures near 27C this afternoon. A system moving into North Dakota this afternoon into this evening will trigger a few showers and thunderstorms.. mainly over North Dakota with some of the activity spreading into southern MB this evening into tonight. There is a slight risk of severe thunderstorms mainly south of the border where low level moisture will be more favourable for stronger storms. The weather system will slowly move across southern MB on Friday bringing more widespread showers over southern MB.. with 5-15 mm of rain possible over most areas. Some leftover showers on Saturday will give way to dry weather by Sunday.. with temperatures still remaining above normal into next week.

Sunday, September 06, 2009

Our stretch of dry warm weather will come to end Monday night into Tuesday as a slow moving cold front crosses southern MB. This front will trigger a band of showers and thunderstorms that will move into southwest MB by Monday evening, reaching the Red River valley overnight Monday into Tuesday morning. In general, most localities in southern MB should be seeing 10-20 mm of rain Monday night through Tuesday as this front crosses through. However, models are indicating that some of the rainfall could be heavy, with local rainfall amounts of 50 mm or more possible especially across SW MB into the Interlake area. The showers are expected to move east of the RRV Tuesday evening, with drier and slightly cooler weather for the rest of the week.

Friday, September 04, 2009

It looks like Mother Nature is making up for her prolonged memory lapse this summer, with a nice warm finish to the summer holidays this weekend. The warm weather of the past few days will continue today and through the holiday weekend with temperatures in the upper 20s, possibly hitting 30C Saturday and Sunday. Labour Day Monday should continue to see warm temperatures, but a cold front is expected to push through late Monday into Monday night, triggering a few showers and thunderstorms as it crosses southern MB. The unsettled weather is expected to move out Tuesday with drier and slighly cooler weather as the kids head back to school. Long range guidance is indicating above normal temperatures returning by mid September.

Tuesday, September 01, 2009

August was another cooler than normal month in Winnipeg.. the 9th consecutive month below normal. The average temperature for the month at YWG airport was 17.3C, or 1.2C below the normal August average of 18.5C. This comes on top of a very cool July (16.5C) and cool June (15.6C), with a 3 month summer average of only 16.5C, or nearly 2C below the normal summer average of 18.3C. This puts it just behind the summers of 1985 and 1883 as the 7th coolest summer in Winnipeg since records began in 1873.

Looking at the 3 month temperature graph for the "summer" of 2009, one can see the only warmth was a 2 week stretch in June and a 4 day hot spell in mid August (the 33C reading on Aug 27th is erroneous) Cool weather dominated most of the summer, especially July which did not break the 30C mark.

August now marks the 9th consecutive month below normal in Winnipeg.. the longest such streak since another 9 month stretch between Dec 1949 and August 1950.